[gentooguy]

Long story short my fuel pressure regulator sprang a leak. I replaced the regulator with a new VDO Continential part. Everything seemed alright with no leaks. On my way home from work with just a bit less than half a tank the car stalled out and I couldn't get it started again (got stuck in a really bad spot). I had my wife come out with some gas I put a little in and tried starting the car and it fired right up again. Got to the gas station and filled the car up all the way. Now it's happened to me again exactly at the same tank level that it happened before (I put in a little gas and I can start the car again). Service Engine Soon light comes on and I get codes (what's strange is these codes go away after I fill the tank a bit):

2AAF
2AAF Fuel pump, plausibility
Error will not cause a warning light
Error is not currently present
Test conditions have been completed
Short circuit or signal interruption

Freeze Frame Information
Event 1Odometer 150064kms 93245miles
fuel pressure before mass control valve 4,924.64 hPa
Engine speed 1,440.00 rpm
voltage Kl. 87 13.61 V
injected mass of fuel 5.00 l/h

Event 2Odometer 150072kms 93250miles
fuel pressure before mass control valve 4,967.09 hPa
Engine speed 1,120.00 rpm
voltage Kl. 87 14.22 V
injected mass of fuel 3.00 l/h

Event 3Odometer 150184kms 93320miles
fuel pressure before mass control valve 4,882.18 hPa
Engine speed 1,632.00 rpm
voltage Kl. 87 14.12 V
injected mass of fuel 8.00 l/h

2A16
2A16 DMTL diagnosis module tank leakage, finest leakage
Error will cause a warning light
Error is not currently present

29DC
29DC Cylinder injection switch-off
Error will cause a warning light
Error is not currently present

So do I have a defective fuel pressure regulator? Did I install it wrong. I followed a DIY guide on Youtube. Or did my low pressure fuel pump take a dump? I didn't have this problem with the leaky fuel pressure regulator :-(

Thanks in advance for any insight. I have INPA if more info is needed.

[robthewrench]

It does sound like your low pressure fuel pump is not supplying enough pressure. Before just replacing it, you could try to check to see if it is getting power when the car stalls out.

Weird.

[gentooguy]

I can check that. It's just weird that it seems to stall at a specific fuel level. As soon as I add a bit of gas it starts right up again. For now I have just been keeping the car at above half. Perhaps it's an issue with the level sensor? Tonight I'm going to re-check the install of the fuel pressure regulator and redo everything. Perhaps a fuel level sensor can't move freely. Really not sure. When it does happen to me the car just cranks and cranks and cranks but no start. Then I add fuel and it starts right back up again. Tank shows a bit less than half full when it happens. Definitely weird.

[gentooguy]

The codes were obtained with the BavTech Auto Tool.
The codes were under the Engine Section not the Fuel Pump EKP Module section.
No codes thrown with the EKP Module.

[robthewrench]

One other test to try. When the car stalls out, try jacking up either the front or back to change the fuel sensing level. You may need to try both. This would confirm your idea that the low pressure fuel pump and level sensor (both built into the low pressure fuel pump) is flaky.

[gentooguy]

Thanks I'll try that at least I know the problem can be reproduced and under what circumstances.

[gentooguy]

Ok took another look and pulled out the fuel pressure regulator. I noticed that the assembly that holds the level sensor came off of the spring loaded guide. Not even sure how that happened. I placed it back on the spring loaded guide. Put it everything back and turned on the car. Fired right up and showed 0 gas in tank. So when from half a tank to nothing! Put in a little gas just enough to get to the gas station and filled her up. Shows a full tank. I'll clear my codes and hope for the best now. I'm surprised it's so easy for the level sensor to come off the guide like that. I bought an expensive VDO part brand new. I guess if it's angled a certain way it just slides off. Thanks all! I'll update if everything worked out!
Image is for reference only my part is brand new.

[helphos]

Some people would say this is an old thread, but the earth is billions of years old, so 4 years isnt much time.

My 128i is exhibiting a similar problem. Is your diagnosis that you were actually on empty when your gage showed half a tank?
In my case, I actually have 4 gallons in the tank when it won't start. When I fill the tank, it takes about 10 gallons and starts right up, so I think my issue relates to bad fuel pump.
thanks in advance for an update.

[Ozzie335i]

gentooguy is long gone since 08/21.